Method for forming openings in tubular welded wall panels



Nov. 3, 11970 g; SI R EI'AL 3,537,290

M'ETHOD FOR FORMING OPENINGS IN TUBULAR WELDED WALL PANELS Filed Aug. 12, 1968 3 Sheets-Sheet 1 I NVENTOR. KENNETH 5. GARNER B 205527 6. IVES A 7"7'ORNE 7 Nov. 3, 1970 K, s; GARNER ET L 5 3 METHOD FOR FORMING OPENINGS IN TUBULAR WELDED WALL PANELS F-iled A 12, 1968 s Sheets-Sheet 2 I INVENTOR. KENNETH B. GARNER ROBERT 6. IVES A TTOENEY NOV. 3, 1970 GARNER ETAL 3,537,290

METHOD FOR FORMING OPENINGS IN TUBULAR WELD'ED WALLPANELS Filed Aug. 12,: 1968 3 Sheets-Sheet 5 INVENTOR. KENNETH B. GARNER F76 5 ROBERT 6.11/55 gm AQZM A TTORNE Y United States Patent Ofi'ce 3,537,290 Patented Nov. 3, 1970 US. Cl. 72-324 4 Claims ABSTRACT OF THE DISCLOSURE A method for forming openings in tubular welded wall panels such as used to line the walls of steam generating furnaces. The steps include removing portions of the connecting webbing from the sides of adjacent tubes through which the opening is to be formed, and bending and stretching the tubes by forcing a suitably shaped wedge therebetween to form the desired opening. 7

BACKGROUND THE INVENTION In a modern steam generator facility it is generally the practice to use water cooled walls to line the furnace thereof. These walls consist of parallel, closely spaced, fluidcarrying steel tubes joined one to the other so as to form a gas-tight chamber. Fluid (e.g., water or steam) is circulated through these tubes to absorb heat and keep the walls relatively cool. In order to prevent hot spots and resulting damage to the tubes, cooling fluid flow must be continuously maintained through the tubes. Therefore, when an opening in a furnace wall is required, a tube must not be cut off and plugged, but rather the tube must circumvent the opening so that the coolant flow will not be interrupted.

In a typical furnace wall of a large steam generator, be-

tween 100 and 150 access openings are required for such purposes as inserting soot blowers, allowing pipes to pass in and out of the furnace, instrumentation leads, continuous TV observation, and for direct visual observation. Several methods have heretofore been used to form the necessary access openings without interrupting the required coolant flow. One method requires that individual tubes are formed with appropriate off-set bends by conventional means before the tubes are joined in panels. Another method requires that segments of the tubes in the welded panels where the desired openings are to be formed are removed and short lengths of suitably bent tubes are welded therein. Each of these methods is subject to particular disadvantages. When using the method, which requires the forming of individual tubes with appropriate off-set bends, the tubes of varying lengths and configurations must be individually processed before a given panel can be assembled from these tubes. The tubes must be placed in a predetermined order and predetermined orientation for welding; and panel support fasteners must be adjustable to accommodate the tubes bent out of plane and precisely position same for weld joining into a panel. Additionally, the welding machine for joining prebent tubes into panels must be sufl'iciently sophisticated to interrupt a particular weld whenever a bent tube is approached, pass over the opening or up and oven the bent tube and continue welding beyond the obstruction. It can readily be seen that such a method is inherently more costly and prone to defects than when the panel is formed by joining identical straight tubes of uniform length. As for the method requiring removal of segments of a panel and insertion of suitably formed short tube lengths therein, this method results in very high welding costs due to the increased number of hand welding operations which must occur.

SUMMARY OF THE INVENTION We have devised a method overcoming the disadvantages of the presently existing methods. Our invention involves the combination of bending and stretching of selected straight tubes in a formed welded tube panel to create a desired opening. A suitably shaped wedge is forced between two tubes between which the desired opening is to be formed and from which portions of the interconnecting webbing have been removed. The particular wedge shape is selected so that the combination of the wedge angle and friction force vector will cause the tubes acted upon to move out of the plane of the welded wall panel on a radius as small as possible while permitting bending and stretching thereof without excess flattening or thinning.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a typical tubular welded wall panel having interconnecting Web portions removed from about the tubes between which the desired opening is to be formed;

FIG. 2 is a perspective view of a section of welded wall panel having a completed opening formed therein by the method of this invention;

FIG. 3 is a side elevation of the Wedge arrangement for creating openings in tube panels according to the method of this invention;

FIG. 4- is a front elevation, partly in section, of the wedge arrangement of FIG. 3, upon the completion of foming an opening;

FIG. 5 is a side elevation of a modification of the wedge arrangement of FIG. 3; and

FIG. 6 is a front elevation partly in section of the wedge arrangement of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a tubular welded wall panel P such as typically used as the lining of a steam generator furnace. Fluid carrying tubes 10 are interconnected by web sections 12. In order to form a desired opening in the weld panel P, segments (14, 14, 16) of the web sections 12 must be removed from the edges of adjacent tubes between which the desired opening is to be formed. The segment 16 to be removed from the web sections 12 between the tubes to be bent extends, as at 16', for a distance beyond that of the removed segments 14 adjacent the outer edges of the tubes to be bent. The purpose of the variation in length of the removed segments is to give added strength to the formed opening and prevent failures of the tubes at the initial points of bending. The removal of segments 14 and 16 of the interconnecting web sections 12 may be accomplished by any appropriate means such as torch burning, plunge cutting, or end milling.

The forming of the desired opening according to this invention is accomplished by the forcing of a suitably shaped wedge assembly between adjacent tubes. This causes the tubes to be bent and stretched out of the plane of the welded panel and laterally offset from their original axis (see FIG. 2). FIGS 3 and 4 show a fundamental arrangement for accomplishing this method. Wedge assembly 18 comprises a body 20 having a means 22 for applying a force thereto and a conically shaped surface 24. The tube panel P is placed so that adjacent tubes between which the desired opening is to be formed lie on lower guides 26, 28, the lower guides being supported by base means 30. Guides 26, 28 may surround the tubes 34 being bent as shown in order to control curvature, or may be of any suitable shape (e.g., rolls 44 or FIGS. 5 and 6) so as to facilitate tube bending without causing distortion of the tubes being bent. Conical surface 24 of wedge assembly 18 is then forced between the adjacent tubes to bend and stretch the tubes to form the desired opening,

The conical surface 24,.of wedge assembly 18 is formed so that the combination of the angle of the wedge surface and the friction force vector will cause the tubes being bent to move out of the plane of the panel on a radius as small as possible so as to permit bending and streching of the tubes without excess flattening or thinning thereof.

FIG. 4 shows the suitably shaped conical wedge surface 24 having accomplished the forming of an opening by the bending and stretching of tubes 32 out of the plane of the panel P and laterally olfset from the original tube axis.

Another example of a fundamental apparatus for per- .forming the method of this invention is shown in FIGS.

and 6. A jack means 36 has a piston rod 38 which passes through a suitable opening 40 in a base means 42. Mounted on the base means .42 are guide rolls 44, similar to the lower guides 26, 28 of FIG. 2. which serve to support the welded wall panel P without causing flattening and thinning of the tubes thereof. A wedge assembly 46 comprises a body 48, having a conical surface 48', fastened to the stem 50 of a T assembly by means of fasteners 52. The cross portion 54 of the T assembly is connected to the piston rod 38 by means of a threaded extension 56 from piston rod 38 and'nut means 58. The threaded portion 56 and nut means 58 are accommodated in opening 60 in the stem portion 50 of the T assembly. The operation of this apparatus is as follows. The bod 48 of the wedge assembly 46 is removed from the stem portion 50. Stem portion 50 is passed through the central removed web segment'16 of the tube panel P in which the desired opening is to be formed, the tubes being supported on guide rolls 44, Body 48 is then replaced on stem portion 50 and fastened thereto by fastening means 52. Jack means 36 (which may be of any suitable type such .as hydraulic or pneumatic) are then activated to withdraw piston rod 38 forcing the conical surface 48' of wedge body 48 into contact with the tubes between which an opening is to be formed. Further withdrawal of the piston rod 38 serves to bend and stretch the tubes in the of FIGS. 5 and 6 has the advantage over the fundamental apparatus of FIGS. 3 and 4 in that it may be, more readily made portable.

Thus it can be seen that we have invented a simple and economical method for forming openings in tubular welded wall panels of the type typically used to line furnace walls of steam generators. By bending and stretching existing tubes of a standard tube panel, from which segments of the interconnecting. webbing have. been removed we have eliminated the necessity of complicated welding apparatus required when preformed tubes are used in forming the welded wall panel. Additionally, by this method we avoid the welding defects which can readily develop from interrupted welds and the imperfect alignment obtainable when arranging prebent tubing for welding. Furthermore, we have. eliminated the necessity of the numerous hand welds required when the panel openings are formed by insertion of formed short tube lengths in removed segments of the tube panels. Our method is not only simple and eflicient, but it may readily be made portable so that openings may be formed at any time even after furnace erection.

While we have illustrated and described a preferred embodiment of our invention, it is to be understood that such is merely illustrative and not restrictive and that-variations and modifications may be made therein without departing from the spirit and scope of the invention. We therefore do not wish to be limited to the precise details set forth but desire to avail ourselves of such changes as fall within the purview of our invention. i

We claim:

1. A method for forming openings in tubular welded wall panels, the steps comprising: removing segments of the weld portions interconnecting the tubes between which the opening is to be formed, and forcing a means between said tubes so as to bend and stretch said tubes out of the plane of the wall panel to form the desired opening.

2. The method of claim 1 wherein the step of removing segments of the weld interconnections includes removing a first portion of the weld segment between the tubes through which the opening is to be formed, and removing second and third portions of the weld segments on either a means between said tubes includes placing a guide means beneath the tubes through whichthe opening is to be formed, placing a wedge between said tubes, forcing said wedge between said tubes, and guiding said tubes in said guide means as they are forced apart by said wedge.

4. A method for forming openings in tubular panels used to line furnace walls comprising the steps of placing a wedge between tubes between which said opening is to 8/1923 Moroto 72369 8/ 1965 Smith et a1. 72326 CHARLES W. LANHAM, Primary Examiner R. M. ROGERS, Assistant Examiner US. Cl. X.R. 

